The present invention generally relates to a jointing unit. More particularly, the present invention pertains to a pipe jointing unit for jointing a variety of pipes in a vehicle and the like.
An example of a known type of pipe jointing unit is disclosed in Japanese Utility Model Publication No. Hei 7-24716 published on Jun. 5, 1995. This pipe jointing unit includes a cylindrical joint having a plurality of holes which are formed adjacent to its edge portion so as to extend in the radial direction, a pipe having a flange on the external surface and inserted into the joint at its one end side, a ring-shaped seal member disposed between the inner surface of the joint and the outer surface of the pipe, and a connecting member made of elastic material and disposed between the joint and the pipe. The connecting member includes an annular portion and a plurality of leg portions extending in the axial direction from the annular portion. The annular portion is inserted between the inner surface of the joint and the outer surface of the pipe in such a manner that the ring-shaped seal member is fitted in a stable manner. Each of the leg portions has a protrusion and a groove. The protrusion protrudes outwardly in the radial direction and is fitted into the penetrating holes of the joint to connect the joint and the connecting member. The groove is formed on the inner surface of the leg portion and is engaged with the flange to connect the connecting member and the pipe.
However, in the above-described pipe jointing unit, the inner diameter of the edge portion of the joint is inevitably larger than the outer diameter of the pipe because the ring-shaped seal member in disposed between the inner surface of the joint and the outer surface of the pipe. Therefore, if the pipe swings in the radial direction relative to the joint by virtue of vehicle vibration, errors in the initial assembly and the like, the pipe does not swing so that the edge potion of the joint is the fulcrum, but swings such that each tip of the leg portions of the connecting member is the fulcrum. Because the connecting member is made of elastic material such as a resin, when the pipe swings in the radial direction relative to the joint, each of the leg portions is pushed by the outer surface of the pipe and is deformed outwardly in the radial direction.
If the leg portions are kept deformed toward the outer radial direction for only a short period of time, the leg portions return to undeformed shape by virtue of the elasticity of the elastic material. However, if the leg portions are maintained in the deformed state during a long period of time, the leg portions are unable to return to the undeformed state by virtue of what is referred to as the creep phenomenon of resin and the like.
As a result, the groove in the leg portion is not engaged completely with the flange of the pipe and so the force resisting the pulling out of the pipe from the connecting member is reduced. The pipe may thus be pulled out of the connecting member by vehicle vibration, an increase of the internal pressure of the pipe and the like.
In light of the foregoing, a need exists for a jointing or joining unit of a relatively simple construction that possesses an improved resistance force against pulling the pipe out of the connecting member
A pipe jointing unit in accordance with the present invention includes a cylindrical joint having a plurality of generally radially extending holes formed adjacent to its edge portion, a pipe having a flange on its outer surface and positioned in the joint at its end side, a ring-shaped seal member disposed between the inner surface of the joint and the outer surface of the pipe, and a connecting member made of elastic material. The connecting member has an annular portion and a plurality of leg portions extending in the axial direction from the annular portion. The annular portion of the connecting member is located between the joint and the pipe in such a manner that the ring-shaped seal member is fitted stably. Each of the leg portions has a protrusion and a groove, with the protrusion extending outwardly in the radial direction and fitted into one of the holes to connect the joint and the connecting member. The groove is formed on the inner surface of the leg portion and engages the flange to connect the connecting member and the pipe. A guide member includes a guide portion disposed between the inner surface of the edge portion of the joint and the outer surface of the pipe.
In accordance with the present invention, the guide portion of the guide member is disposed between the inner surface of the edge portion of the joint and the outer surface of the pipe and so the pipe is restricted from swinging in the radial direction relatively against the joint. The pipe is thus inhibited from swinging in such a manner that the tips of the leg portions of the connecting member serve as a fulcrum. If the pipe is swung in the radial direction relatively against the joint, because each of the leg portions cannot be deformed outwardly in the radial direction, it is possible to avoid situations in which the leg portions in the deformed state by virtue of the creep phenomenon of resin are unable to return to the undeformed state. Thus, the reliability of the resistance force against pulling the pipe out of the connecting member by vehicle vibration, an increase in the internal pressure of the pipe and the like is improved.
The guide portion of the guide member preferably has an annular shape and possesses an inner diameter substantially equal to the outer diameter of the pipe and an outer diameter substantially equal to the inner diameter of the edge portion of the joint. With this construction, the pipe is further restricted from swinging in the radial direction relatively against the joint, and the reliability of the resistance force against pulling the pipe out of the connecting member is further improved.
The guide member preferably further includes a plurality of arms extending axially from the guide portion so that the tip portion of each of the arms is able to engage the flange of the pipe, and an engaging portion extending in the axial direction from the guide portion so that the tip portion of the engaging portion is able to engage the outer surface of the edge portion of the joint. The length of each of the arms and the length of the engaging portion are selected so that the flange of the pipe is completely engaged with the groove of the leg portion by the engagement between the flange and the tip portion of each of the arms and so that the guide portion is completely disposed between the inner surface of the edge portion of the joint and the outer surface of the pipe only when the engaging portion is completely engaged with the outer surface of the edge portion of the joint. With this construction, if the groove of the leg portion is not completely engaged with the flange of the pipe by virtue of incomplete insertion of the pipe into the joint, the tip portion of the engaging portion of the guide member cannot be engaged with the outer surface of the edge portion of the joint because the flange is engaged with the tip portion of the arms of the guide member. It is thus possible to determine whether the groove of the leg portion is completely engaged with the flange by checking whether the engaged portion of the guide member is completely engaged with the edge portion of the joint.
It is preferable also that the guide portion of the guide member have an annular corner possessing an arc-shaped cross section and located at the side of the guide portion opposite to the arms. The pipe is thus able to swing in such a manner that the annular corner is the fulcrum. Therefore, compression stress of the pipe at the contact point with the annular corner can be reduced. This improves the reliability and endurance of the pipe itself under the condition of vehicle vibration and the like.
The guide member must be inserted into the joint while the tips of the arms are positioned at a predetermined position relative to the tip of the leg portions in the circumferential direction to avoid contact between the tips of the arms and the tips of the leg portions. It is thus preferable that each of the arms is tapered toward the tip portion of the arm. Thus, even if the guide member is inserted into the joint with the tip of the arms slightly shifted relative to the predetermined or correct position in the circumferential direction, the guide member is automatically moved toward the predetermined or correct position in the circumferential direction while the tapered tip of the arms is guided on the tip of the leg portions. Thus, the guide member can be completely inserted into the joint at the predetermined position in the circumferential direction. Thus, under blind assembly work, the efficiency of the work can be improved.
The tip of each of the arms and the tip of each of the leg portions are shaped so that the tip of the arms is not elastically deformed in the radial direction when the guide member is pressed in the axial direction under the condition that the tip of each of the arms and the tip of each of the leg portions contact each other. With such a construction, even if the guide member is inserted into the joint under the condition that the tip of each of the arms and the tip of each of the leg portions contact each other, because the tip of the arms is not elastically deformed and the guide member cannot be completely inserted into the joint, the engaged portion cannot be engaged with the edge portion of the joint. Therefore, irregular or incorrect assembly can be avoided.
According to another aspect of the invention, a pipe jointing unit includes a tubular joint in which is formed at least one through hole adjacent an edge portion of the tubular joint, a pipe positioned in the joint having an outer surface on which is located a flange, a ring-shaped seal member disposed between the inner surface of the joint and the outer surface of the pipe, an elastic connecting member, and a guide member. The connecting member includes an annular portion and at least one leg portion extending axially from the annular portion, with the annular portion positioned between the joint and the pipe. A portion of the leg portion engages the flange on the pipe to connect the connecting member and the pipe and a portion of the leg portion engages the hole in the joint to connect the joint and the connecting member. The guide member has a guide portion disposed between an inner surface of the edge portion of the joint and the outer surface of the pipe.